The Data-Over-Cable Service Interface Specification (DOCSIS) was established by cable television network operators to facilitate transporting data traffic, primarily Internet traffic, over existing cable television (CATV) networks. In addition to transporting data traffic, as well as television content signals over a CATV network, multiple services operators (MSO) also use their CATV network infrastructure for carrying voice, video on demand (VoD) and video conferencing traffic signals, among other services.
In an upstream receiver, such as is used in a cable modem termination system (CMTS), an increase in the number of taps used in an adaptive equalizer can result in an improved modulation error ratio (MER), and thus, reduced forward error correction (FEC) errors, when there are significant upstream channel impairments (e.g., frequency roll-off, channel micro-reflections, etc.). However, the use of additional taps can negatively impact the noise margin on the upstream channel when there are no upstream impairments and can reduce the number of available hardware resources used to filter signals (e.g., multipliers and delay taps). Current upstream CMTS receivers use a global register setting that is set by software for all types of upstream channel conditions. Typically, the register setting is set for worst case upstream conditions. Therefore, when the upstream channel is relatively clean, filtering resources are likely being used unnecessarily and noise margins are likely being lost. It is desirable to improve upon the techniques for determining a number of equalizer taps to be used in an upstream receiver.
Like reference numbers and designations in the various drawings indicate like elements.